It is possible to manage access to a collective resource by means of an interface. The interface uses an access scheme according to which the functions can access the collective resource.
One possible access scheme is characterized by an order of priority. A function must make a request to access the collective resource. The interface collects all the requests. Amongst the functions having a current request, it enables the function having the highest priority to access the collective resource. Assume once again that a functional system comprises three functions A, B and C. The order of priority may be A, B, C. In this case, function A will have access to the collective resource independently of the fact that a request from function B or C is current. Function B would have access to the collective resource provided that a request from function A is not current. Function C would have access to the resource provided that a request from function A or B is not current. Such an access scheme will be referred hereinafter as a priority access scheme.
The priority access scheme is mentioned in European patent application published under the number 1081603-A1. In principle, each function must have sufficient access to the collective resource for it to be able to be implemented correctly. Access of any function to the collective resource is determined by two factors: firstly, the access capacity offered by the collective resource and secondly the access scheme applied.
In principle it is possible to guarantee sufficient access to each function by ensuring that the collective resource offers a relatively high access capacity. However, the greater the access capacity (bandwidth, speed) offered by the collective resource, the more expensive the collective resource will in general be.
The requirement for access of a function may vary over time. It is possible that another function may need to access the collective resource intensively during a certain period and that this function does not require such an intensity of access during another period. The priority access scheme gives access to the collective resource on demand. This scheme therefore affords flexibility and consequently more effective use of the collective resource. The priority access scheme in fact requires less access capacity for the collective resource compared with a fixed access scheme in which the access model comprises several intervals of time each allocated to a certain function. Consequently the priority access scheme in principle affords a reduction in cost with regard to the collective resource.